While high-load
resistance training increases muscle
hypertrophy, the intramuscular
protein responses to this form of training remains largely unknown. In the current study, recreationally resistance-trained college-aged males (N = 15; mean ± SD: 23 ± 3 years old, 6 ± 5 years training) performed full-body, low-volume, high-load [68-90% of one repetition maximum (1RM)]
resistance training over 10 weeks. Back squat strength testing, body composition testing, and a vastus lateralis biopsy were performed before (PRE) and 72 h after the 10-week training program (POST). Fiber type-specific cross-sectional area (fCSA), myofibrillar
protein concentrations, sarcoplasmic
protein concentrations,
myosin heavy chain and actin
protein abundances, and muscle tissue percent fluid were analyzed. The abundances of individual sarcoplasmic
proteins in 10 of the 15 participants were also assessed using proteomics. Significant increases (p < 0.05) in type II fCSA and back squat strength occurred with training, although whole-body fat-free mass paradoxically decreased (p = 0.026). No changes in sarcoplasmic
protein concentrations or muscle tissue percent fluid were observed.
Myosin heavy chain protein abundance trended downward (-2.9 ± 5.8%, p = 0.069) and actin
protein abundance decreased (-3.2 ± 5.3%, p = 0.034) with training. Proteomics indicated only 13 sarcoplasmic
proteins were altered with training (12 up-regulated, 1 down-regulated, p < 0.05). Bioinformatics indicated no signaling pathways were affected, and
proteins involved with metabolism (e.g.,
ATP-PCr, glycolysis, TCA cycle, or beta-oxidation) were not affected. These data comprehensively describe intramuscular
protein adaptations that occur following 10 weeks of high-load
resistance training. Although previous data from our laboratory suggests high-volume
resistance training enhances the
ATP-PCr and glycolytic pathways, we observed different changes in metabolism-related
proteins in the current study with high-load training.